Multiscale interactions predict stress in adult zebrafish (Danio rerio).
June 2016 – Clemson, South Carolina (ISEP)
Are movement patterns specific to physiological states such as stress? In the present study zebrafish (a well-established translational model in neuroscience) were exposed to a stress procedure (15-minute isolation and confinement) followed by a 15 minute behavioral stress measure (open-field task). Swim behavior in the open field was analyzed with idTracker, a MATLAB-based tracking software, and by video frame differencing using ImageJ software. Video differencing compares average pixel intensity between neighboring video frames, and has been successfully employed as a measure of temporal change in human coordination tasks. The multifractal spectrum width extracted both from movement trajectories and from the differenced time series predicted stress equally well using a mixed-effects logistic regression model. In particular, multifractality contributed to the prediction of stress response above and beyond standard deviation and total path length. The present study demonstrated that 1) video-based tracking methods are a cost effective means for assessing the presence of psychophysiological states based on movement trajectory analysis and video differencing, and 2) that stress behavior exhibits multiscale variability captured in movement trajectories. Implications for developing novel procedures for diagnosing stress based on monitoring multiscale interactions in motor behavior are considered.
Zebrafish and conditioned place preference: A translational model of drug reward.
June, 2015 – Victoria, Canada (IBNS)
Addiction and substance abuse amass hundreds of billions of dollars annually in costs associated with healthcare, crime and lost productivity, solely within the United States. Sanctioned drugs (e.g., alcohol, nicotine and caffeine) are used and abused frequently, the use of which may result in psychological and/or physiological dependence. Efficacious treatments for substance use disorders remain few in number. A better understanding of environmental, genetic, pharmacological and neurobiological mechanisms implicated in the pathogenesis of addiction will facilitate treatment development. Animal models such as the zebrafish (Danio rerio) have gained momentum within various domains of translational research, and as a model of complex brain disorders (e.g., addiction). Behavioral quantification within the conditioned place preference (CPP) paradigm serves as a measure of the rewarding qualities of a given substance. If animals develop an increase in preference for the drug-paired environment, it is inferred that the drug has rewarding properties. The current study reports CPP behavior in adult zebrafish following acute (1 day) or chronic (7 days) exposure to alcohol (0.0%, 0.25%, 0.50% or 1.00% vol/vol), caffeine (0 mg/l, 50 mg/l, 100 mg/l and 150 mg/l) and nicotine (0mg/L, 2.5 mg/l, 5 mg/l and 10 mg/l).
Assessing the effects of light dark manipulation and caffeine exposure on zebrafish sleep behavior.
June 2015 – Victoria, Canada (IBNS)
Zebrafish are a well-known and widely used model organism in behavioral research; several neurotransmitter systems and neuropeptides are conserved in this species, allowing for a comparative understanding of sleep and sleep structures. Previous study has revealed changes in gene expression following an exposure to constant light and constant dark conditions. Here, we expand on the literature and work to build upon the current understanding of sleep behavior in this small teleost fish. We assessed sleep and wake behavior within groups of three fish to alleviate the stress effects of being removed from the shoal. Sleep and wake behavior of the groups were analyzed following three sleep-wake cycle manipulations: (1) constant light conditions, (2) constant dark conditions, and (3) constant light conditions, paired with the administration of an adenosine antagonist. Following sleep-wake cycle manipulations, animals were transferred to an additional apparatus for either novel tank testing or cortisol measurements. Antagonism of adenosine during prolonged light exposure produces both behavioral and physiological changes. Cortisol expression was unchanged in animals exposed to constant light conditions, and was elevated in animals exposed to both caffeine and constant light. Animals in the constant light condition tended not to explore regions of their environment when placed in a novel tank; they also tended to move erratically, and dwell in the lower region, when compared to animals in other light/dark manipulation conditions.
Addiction and substance abuse amass hundreds of billions of dollars annually in costs associated with healthcare, crime and lost productivity, solely within the United States. Efficacious treatments remain few in number, the development of which will be facilitated by comprehension of environmental, genetic, pharmacological and neurobiological mechanisms implicated in the pathogenesis of addiction. Animal models such as the zebrafish (Danio rerio) have gained momentum within various domains of translational research, and as a model of complex brain disorders (e.g., drug abuse). Behavioral quantification within the conditioned place preference (CPP) paradigm serves as a measure of the rewarding qualities of a given substance. If the animal develops an increase in preference for the drug paired environment, it is inferred that the drug has positive-reinforcing properties. Here we present the utility of the zebrafish model and report CPP behavior following a single exposure to 0.0%, 0.25%, 0.50%, and 1.00% alcohol and 0 mg/L, 50 mg/L, 100 mg/L and 150 mg/L caffeine.
The zebrafish (Danio rerio) animal model is steadily gaining popularity in behavioral neuroscience research. This species’ stress response has been reported to induce observable behavioral alterations within a number of paradigms adopted from the rodent literature. In this study, zebrafish were exposed to an acute stressor, consisting of isolation and confinement in 100mL of water within a 250mL beaker. Studies that pharmacologically manipulate zebrafish behavior often deliver water soluble compounds via a bath solution within a beaker to be absorbed through the gills. Previous research in our lab has revealed that the beaker stress paradigm (adapted from the bath solution method) reliably stimulates the release of cortisol, a physiological indicator of stress. We show here that this robust stress response is correlated with significant behavioral changes that have been observed within three well-utilized tasks in the literature, the novel tank dive, light-dark discrimination and the open-field. A separate experiment sought to better understand cortisol expression as a function of time. Following exposure to the stressor, animals were placed in an aquatic open-field testing tank, and whole-body cortisol levels were subsequently measured over various time intervals during a 60 minute period. Mean cortisol levels were found to be highest during minutes 10 and 15 in the open field, and at minute 20, cortisol levels significantly decreased and remained relatively stable throughout minutes 25, 30, 45, and 60. All time points were also found to be significantly greater than baseline. Preliminary analysis reveals a strong correlation between cortisol levels and behavior change over time. Stress induced behavioral phenotypes; correlated with a measureable endocrine response, help to establish the zebrafish as a viable neurobehavioral model of stress and anxiety.